text: // Copyright (c) 2015 - 2017 Uber Technologies, Inc.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  
  export default `\
  #define SHADER_NAME graph-layer-vertex-shader
  
  attribute vec4 positions;
  attribute vec4 colors;
  attribute vec3 pickingColors;
  
  uniform float lightStrength;
  uniform float opacity;
  
  varying vec4 vColor;
  varying float shouldDiscard;
  
  void main(void) {
  
    // fit into a unit cube that centers at [0, 0, 0]
    vec3 position_commonspace = project_position(positions.xyz);
    gl_Position = project_common_position_to_clipspace(vec4(position_commonspace, 1.0));
  
    // cheap way to produce believable front-lit effect.
    // Note: clipsspace depth is nonlinear and deltaZ depends on the near and far values
    // when creating the perspective projection matrix.
    vec4 position_vector = project_common_position_to_clipspace(vec4(position_commonspace, 0.0));
    float fadeFactor = 1.0 - position_vector.z * lightStrength;
  
    vColor = vec4(colors.rgb * fadeFactor, colors.a * opacity) / 255.0;;
  
    picking_setPickingColor(pickingColors);
  
    shouldDiscard = positions.w;
  }
  `;
  